As a conventional insert part weld molding method, a method is known in which by chamfering a circumferential edge of a welding bed provided in a flange-like shape on a welded portion of an insert part, the welding bed is brought into close contact with and welded to an expanding parison during molding of a blow molded object (fuel tank) (for example, refer to Patent Document 1).
Patent Document 1: Japanese Patent Application No. 2003-236920